CNC Mill Modification

(All contents on one page)

 

The Problem: a limited y-axis working length on the stock milling machine

(Note: study the picture above or else the description below will sound wordy and make no sense)

The stock Sherline milling machine has a limited y-axis range due to work piece interference with the z-axis column mount. Even though the y-axis bed can move along the entire length of the lead screw, the real workable area is determined by the distance between the spindle centerline and the back of the z-axis column mount( labeled as the "y-axis true work length" above).  Riser blocks could be added to lengthen the distance between the spindle centerline and the z-axis column mount but this would put increase stress and friction on the z-axis dove tail. The project below improves on the y-axis true work length by using custom aluminum supports in place of the stock z-axis mount. The project also adds another significant improvement by allowing the milling machine to be easily converted into a lathe.

The Solution (side view)

Side-View Legend

yellow the X-axis and Y-axis linear slides
white an aluminum plate forming the X-Y table surface
orange the spindle, spindle motor, spindle speed control and rotary column attachment
pink Z-axis linear slide
gray spacer block
blue horizontal aluminum cross members to support the spindle, motor and Z-axis slide
red two vertical aluminum support posts for the horizontal cross members. the posts have a series of vertical holes that allow the cross members to be mounted at different heights
green an aluminum base plate providing a mount for the vertical support posts, the X-Y axis linear slides and the lathe mounting structures
   
My stock Sherline CNC machine mounted to a huge aluminum base plate. I'm going to use the original machine to create parts for the new machine!
   
I'm using some C-clamps to secure some aluminum stock for milling. One of the biggest challenges in CNC milling is finding a good way to mount the stock securely.
   
Here I am squaring off the ends of some aluminum stock that will become part of the new vertical axis mounts.
   
This is my first attempt at squaring off one end of an aluminum block. I used an end mill set to the top of the stock and then repeatedly varied the z-depth by a quarter inch during each horizontal sweep of the end mill. This technique resulted in unwanted visible striations. 
   
My second attempt at squaring off the aluminum block resulted in a much smoother machined surface. In this technique I set the end mill to the maximum depth of the stock thickness. I then slowly brought the end mill in towards the stock during each horizontal sweep of the end mill.
   
My new z-axis mount! Here I am positioning an aluminum plate that will be machined for my lathe conversion.  Click here for my lathe conversion